CANCER AND FOOD

NEGATIVE IMPACT

• Promoter of carcinogenesis
• High saturated fat diet - increases risk of tumours
• High fat diet may increase secretion of bile acids which can form mutagenic compounds
• Type + quantity of fat in the diet increases levels of hormones e.g. oestrogen in blood + fuels development of cancer
• High intake of fat stimulates production of bile salts in gut - high levels assoc. with colon cancer
• PUFA (N-6 Fatty acids)- promote tumour + cancer development

POSITIVE IMPACT

• N-3 Fatty acids from fish oils - protect against certain types of cancer
• MUFA in olive oil (oleic acid) acts as antioxidant, protects DNA + reduces growth of cancer cells 

• Research suggests eating red meat daily is linked with DNA damage - raises risk of bowel cancer due to N-Nitro compounds
• Meat contains higher level of sat. fat than many non-meat alternatives - increases risk of obesity + overweight - risk of breast cancer due to increased hormone levels
• High fat diet increases secretion of bile acids which form mutagenic compounds
• Nitrogenous residues from meat digestion may be metabolised in large bowel to produce ammonia - links with bowel cancer
• Charring of meat/burnt foods contribute carcinogens e.g. aromatic hydrocarbons which generate sper oxide free radicals (damage DNA + leads to development of cancer)
• Cured meats promote risk of colorectal, lung, breast cancer
• Nitrites and nitrates added to processed meats- linked to colorectal cancer
• Salt in processed meats- increases risk of damage to stomach lining + increases sensitivity of stomach to carcinogens e.g. nitrates

• High osmotic activity linked to gastritis resulting in early damage to mucosa + acts as gastric irritant - leads to degeneration of acid-secreting glands in stomach + increases acid secreting bacteria which produce carcinogenic substances known as NITROSAMINES
• Damages lining of stomach + causes inflammation or makes stomach lining more sensitive to carcinogens e.g. nitrates
• Can interact with stomach bug (HELICOBACTER PYLORI) - causes stomach cancer+ulcers

• Bacteria in bowel interact with fibre to produce chemicals including BUTYRATE - changes bowels condition so tumours are less likely to develop
• Fibre triggers production of helpful chemicals + dilutes contents of stools +increases their bulk due to increase in colonic bacteria + freq. of bowel movements - reduces contact time between bowel + stools, decreasing amount of carcinogenic chemicals absorbed through lining of gut
• NSP reduces pH of bowel and allows bile acids to bond to calcium preventing them from being converted to mutagenic secondary bile acids
• NSP can protect against colon + rectum cancer
• NSP - protective for people who consume lots of red meat
• Sol. fibre mops up toxins + other harmful carcinogenic substances which are in contact with mucosa for shorter time - lowers risk of bowel cancer
• NSP lowers levels of oestrogen in blood - decreases risk of breast cancer

Antioxidants

• vitamin A,C,E - linked to prevention of oxidative damage to DNA by free radicals

Phytochemicals: protective chemicals in plant food sources

• Examples of Phytochemicals
• Lycopene - tomatoes - protect against stomach, cervix, prostate cancer
• Glucosinolates - most veg. - helps liver in detoxifying function + may help reduce tumour growth in breast,liver,stomach
• Flavonoids - citrus fruits - protective against oxidative damage
• Phyto-oestrogens - leek,broccoli,asparagus - slows progression of cancer

NSP

• Increases bulk + faster transit time for waste through large intestine - carcinogenic substances more dilute + have less contact time

• Limits inclusion of antioxidants within diet which have capacity to scavange for free radicals. Oxygen free radicals can react with DNA to cause breaks in DNA chain- initiates carcinogenesis

May limit inclusion of NSP

• Low levels of NSP promotes colon cancer as NSP is req. to increase bulk + faster transit time through colon
• Lack of NSP causes potentially harmful carcinogenic substances to be present in more concentrated form + may be in contact with colonic mucosa for longer time

May indicate less healthy diet with higher fat content

• Increases risk of breast cancer - result of weightgain + enhanced hormone levels
• Diet low in protective antioxidants to combat free radicals

Non-organic fruit + veg

• could contain high levels of pesticides/fertilizers - increase hormone related cancers

• Oxygen free radicals react with DNA to cause breaks in DNA chain + mutation - initiates carcinogenesis + antiox. have capability to scavage free radicals

Vitamin A - reduces lung cancer

Vitamin C - repairs damaged DNA caused by free radicals + prevents gene mutation leading to cancer

Vitamin E - smokers should ensure they have an adequate intake of Vitamin E

Selenium - protects against prostate + digestive cancers

• Supplementation of antiox. don't appear to reduce cancer risk - best source fruit + veg